Rotating edge-field driven processing of chiral spin textures in racetrack devices

Alexander F Schäffer,Michael Thorwart,Roland Wiesendanger,Jamal Berakdar,Pia Siegl,Thore Posske,Elena Y Vedmedenko,Martin Stier

doi:10.1038/s41598-020-77337-y

Alexander F Schäffer, Michael Thorwart + Show 6 more

Open Access

https://doi.org/10.1038/s41598-020-77337-y

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Abstract

Topologically distinct magnetic structures like skyrmions, domain walls, and the uniformly magnetized state have multiple applications in logic devices, sensors, and as bits of information. One of the most promising concepts for applying these bits is the racetrack architecture controlled by electric currents or magnetic driving fields. In state-of-the-art racetracks, these fields or currents are applied to the whole circuit. Here, we employ micromagnetic and atomistic simulations to establish a concept for racetrack memories free of global driving forces. Surprisingly, we realize that mixed sequences of topologically distinct objects can be created and propagated over far distances exclusively by local rotation of magnetization at the sample boundaries. We reveal the dependence between chirality of the rotation and the direction of propagation and define the phase space where the proposed procedure can be realized. The advantages of this approach are the exclusion of high current and field densities as well as its compatibility with an energy-efficient three-dimensional design.

Highlights

Distinct magnetic structures like skyrmions, domain walls, and the uniformly magnetized state have multiple applications in logic devices, sensors, and as bits of information
Magnetic logic devices based on magnetic domain walls (DW) were introduced in 20051, where DWs were driven by rotating magnetic fields in magnetic stripes
We investigate whether local magnetic fields, instead of global effects[11], can be used to create non-collinear topological magnetic quasiparticles as DWs or skyrmions

Summary

Introduction

Distinct magnetic structures like skyrmions, domain walls, and the uniformly magnetized state have multiple applications in logic devices, sensors, and as bits of information. We reveal the dependence between chirality of the rotation and the direction of propagation and define the phase space where the proposed procedure can be realized The advantages of this approach are the exclusion of high current and field densities as well as its compatibility with an energy-efficient three-dimensional design. The control of the domain walls by electric currents was proposed in memory d evices[2] Since that time, both driving mechanisms were refined and extended to chiral objects[3,4,5,6]. We have shown theoretically[7] that certain topological magnetic structures can be created without the help of global fields or currents, only by imposing time-dependent boundary conditions. We especially consider systems with a relevant Dzyaloshinskii-Moriya interaction (DMI), potentially hosting both chiral DWs and skyrmions

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